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Xenascus dubius
Xenascus dubia (Corradini, 1973) Lentin and Williams, 1993
Originally Phoberocysta, subsequently Phoberocysta?, thirdly (and now) Xenascus. The combination Xenascus dubia was not validly published by Monteil, 1991, since he did not provide a complete citation for the basionym.
Lentin and Williams, 1993, questionably included this species in Xenascus.
Holotype: Corradini, 1973, pl.29, fig.6a-b
Locus typicus: Viano, Reggio Emilia, Italy
Stratum typicum: Senonian
Original diagnosis: Corradini, 1973, p. 182: ?Phoberocysta dubia
Cyst flattened dorso- ventrally with smooth subspherical endophragm sometimes bilobated antapically. Pericoel in form of a wing lamella, irregular in outline, surrounding the whole capsule. Antapical horn very reduced. Processes heterogenous in shape, not well developed. Archeopyle apical. Dimensions-Holotype: width of the capsule 58 µm, length (without apical calotte) 54 µm, width of the periphragm 90 µm, length 70 µm. Range: width of the capsule 54-(57)-60 µm, length 50-(55)-62 µm, width of the periphragm 75-(83)-90 µm, length 60-(76)-90 µm.
Original description: Corradini, 1973, p. 182: ?Phoberocysta dubia
The two antapical lobes of the inner body are, when present, differently developed. The periphragm is closely appressed to the endophragm at the dorsal and ventral side of the cyst. The walls are separated along the circumpherential zone by an irregularly developed pericoel. The membrane is normally wide and increases or decreases, sometimes causing discontinuity on the pericoel. Processes are numerous, but not well developed, slender, more or less branched and irregularly arranged on the whole periphragm. The antapical horn, corresponding in position to the larger antapical lobe, is always poorly developed and hardly distinguishable on the external wing. Cingulum and tabulation not recognised. Apical archeopyle lacking in angular margins.
Originally Phoberocysta, subsequently Phoberocysta?, thirdly (and now) Xenascus. The combination Xenascus dubia was not validly published by Monteil, 1991, since he did not provide a complete citation for the basionym.
Lentin and Williams, 1993, questionably included this species in Xenascus.
Holotype: Corradini, 1973, pl.29, fig.6a-b
Locus typicus: Viano, Reggio Emilia, Italy
Stratum typicum: Senonian
Original diagnosis: Corradini, 1973, p. 182: ?Phoberocysta dubia
Cyst flattened dorso- ventrally with smooth subspherical endophragm sometimes bilobated antapically. Pericoel in form of a wing lamella, irregular in outline, surrounding the whole capsule. Antapical horn very reduced. Processes heterogenous in shape, not well developed. Archeopyle apical. Dimensions-Holotype: width of the capsule 58 µm, length (without apical calotte) 54 µm, width of the periphragm 90 µm, length 70 µm. Range: width of the capsule 54-(57)-60 µm, length 50-(55)-62 µm, width of the periphragm 75-(83)-90 µm, length 60-(76)-90 µm.
Original description: Corradini, 1973, p. 182: ?Phoberocysta dubia
The two antapical lobes of the inner body are, when present, differently developed. The periphragm is closely appressed to the endophragm at the dorsal and ventral side of the cyst. The walls are separated along the circumpherential zone by an irregularly developed pericoel. The membrane is normally wide and increases or decreases, sometimes causing discontinuity on the pericoel. Processes are numerous, but not well developed, slender, more or less branched and irregularly arranged on the whole periphragm. The antapical horn, corresponding in position to the larger antapical lobe, is always poorly developed and hardly distinguishable on the external wing. Cingulum and tabulation not recognised. Apical archeopyle lacking in angular margins.